This invention relates to tagged articles and to a method and apparatus for producing such articles. The invention finds particular, but not exclusive, use in the production of infusion packets containing infusible material, such as tagged tea bags.
Tea bags consist of doses of dried and shredded tea leaves, sealed in compartments made of a readily permeable web material, generally referred to as paper although it may have a significant plastics content and may even be constituted by a perforated or permeable plastics material. Tea bags and other infusion bags are often provided with a tag, attached to the bag itself through a thread, to make it more convenient for the user to handle the bag.
Examples of such tagged bags can be found in GB-A-2052428, U.S. Pat. No. 2,925,171 and U.S. Pat. No. 2,335,159. In the first of these, the thread is pre-packed within the tag and the tag is then inserted into a pocket in the bag itself. The arrangement is intended to avoid entangling the threads in a package of bags such as might happen if all the tags hung freely from their threads. The solution to that problem offered by the disclosure is, however very elaborate and increases costs very considerably.
U.S. Pat. No. 2,925,171 provides examples of infusion bags with freely hanging tags. The thread attaching the tag to its bag may be knotted onto the end of the bag, so also closing the bag but incidentally also restricting the volume of the bag when its contents swell during infusion. Alternatively, the thread must be attached to the bag by a staple or clip.
In the case of U.S. Pat. No. 2,335,159 one or more threads are laid between the two web layers that form the compartments of a series of bags and the compartments are separated from each other by seals across the webs in the regions where the threads cross the web. This form of product is difficult to manufacture--for example the threads must be correctly located between the webs before the infusible material can be sealed in place--and may not be particularly convenient since the length of the thread is set by the size of the bag.
Another method of producing tagged tea-bags is disclosed in U.S. Pat. No. 2,556,383 in which a thread is drawn onto a periphery of a rotating wheel on which there are a series of spaced tag seats. Tags having pre-punched flaps are then slid sideways into the seats over which the thread already runs, the thread being engaged by the flaps as the tags are inserted. The flaps are next pressed down onto the thread to secure the tags and thread together, and following this the thread between each adjacent pair of tags is drawn into a recess in the wheel to form a loop. The thread between successive tags is next cut as the tags are carried round to the bottom of the wheel. Here the loops of thread depend below the wheel and are attached to respective tea-bags which are conveyed below the wheel in synchronism with its rotation.
Such an arrangement provides a continuous production process but has many disadvantages. In particular, the tags cannot be very securely attached to the thread because they rely on the purely mechanical connection offered by the flaps, which must also allow the thread to be drawn through them when the loops are formed. There is also the difficulty of ensuring alignment between the loosely hanging loops and the bags passing beneath the wheel, which makes it impossible to achieve fast and reliable production.